Some hybrid vehicles use a primary power source like an electric motor for the majority of the vehicle's propulsion needs and supplement that with an auxiliary power source, such as an internal combustion engine, as needed. Certain environmental factors, such as steep inclines on mountain roads, can present unique challenges for hybrid vehicles.
For example, when a hybrid vehicle is attempting to climb a mountain road with a significant grade, the electric motor may exhaust or at least diminish much of the stored charge on the battery. If the state-of-charge (SOC) of the battery falls beneath a certain threshold, the hybrid vehicle may have to rely on the internal combustion engine to provide supplemental propulsion power. In order to accomplish this task without resulting in a significant reduction in power that is noticeable to the driver, a hybrid vehicle operating mode specifically tailored to environments such as this may need to be employed.